// ========================================================================
// Copyright (c) 2004-2009 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses.
// ========================================================================

package org.eclipse.jetty.server.handler;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.util.component.LifeCycle;

/* ------------------------------------------------------------ */
/**
 * A <code>HandlerWrapper</code> acts as a {@link Handler} but delegates the {@link Handler#handle handle} method and {@link LifeCycle life cycle} events to a delegate. This is primarily used to implement the <i>Decorator</i> pattern.
 */
@SuppressWarnings({ "unchecked", "rawtypes" })
public class HandlerWrapper extends AbstractHandlerContainer
{

	protected Handler _handler;

	/* ------------------------------------------------------------ */
	/**
     *
     */
	public HandlerWrapper()
	{}

	/* ------------------------------------------------------------ */
	/**
	 * @return Returns the handlers.
	 */
	public Handler getHandler()
	{
		return _handler;
	}

	/* ------------------------------------------------------------ */
	/**
	 * @return Returns the handlers.
	 */
	public Handler[] getHandlers()
	{
		if (_handler == null)
			return new Handler[0];
		return new Handler[] { _handler };
	}

	/* ------------------------------------------------------------ */
	/**
	 * @param handler Set the {@link Handler} which should be wrapped.
	 */
	public void setHandler(Handler handler)
	{
		if (isStarted())
			throw new IllegalStateException(STARTED);

		Handler old_handler = _handler;
		_handler = handler;
		if (handler != null)
			handler.setServer(getServer());

		if (getServer() != null)
			getServer().getContainer().update(this, old_handler, handler, "handler");
	}

	/* ------------------------------------------------------------ */
	/*
	 * @see org.eclipse.thread.AbstractLifeCycle#doStart()
	 */
	@Override
	protected void doStart() throws Exception
	{
		if (_handler != null)
			_handler.start();
		super.doStart();
	}

	/* ------------------------------------------------------------ */
	/*
	 * @see org.eclipse.thread.AbstractLifeCycle#doStop()
	 */
	@Override
	protected void doStop() throws Exception
	{
		if (_handler != null)
			_handler.stop();
		super.doStop();
	}

	/* ------------------------------------------------------------ */
	public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
	{
		if (_handler != null && isStarted())
		{
			_handler.handle(target, baseRequest, request, response);
		}
	}

	/* ------------------------------------------------------------ */
	@Override
	public void setServer(Server server)
	{
		Server old_server = getServer();
		if (server == old_server)
			return;

		if (isStarted())
			throw new IllegalStateException(STARTED);

		super.setServer(server);

		Handler h = getHandler();
		if (h != null)
			h.setServer(server);

		if (server != null && server != old_server)
			server.getContainer().update(this, null, _handler, "handler");
	}

	/* ------------------------------------------------------------ */
	@Override
	protected Object expandChildren(Object list, Class byClass)
	{
		return expandHandler(_handler, list, byClass);
	}

	/* ------------------------------------------------------------ */
	@SuppressWarnings("null")
	public <H extends Handler> H getNestedHandlerByClass(Class<H> byclass)
	{
		HandlerWrapper h = this;
		while (h != null)
		{
			if (byclass.isInstance(h))
				return (H)h;
			Handler w = h.getHandler();
			if (w instanceof HandlerWrapper)
				h = (HandlerWrapper)w;
			else
				break;
		}
		return null;

	}

	/* ------------------------------------------------------------ */
	@Override
	public void destroy()
	{
		if (!isStopped())
			throw new IllegalStateException("!STOPPED");
		Handler child = getHandler();
		if (child != null)
		{
			setHandler(null);
			child.destroy();
		}
		super.destroy();
	}

}
